Metal fixture for typewriter desks



July 24, 1951 M. Fox A 2,561,505

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METAL FIXTURE FOR TYPEWRITER DEsxs 3 Sheets-Sheet 2 Filed April 27, 1950M. FCX

METAL FIXTURE FOR TYPEWRITER DESKS July 24, 1951 Filed April 27, 1950 3Sheets-Sheet 5 FIEL 7 y mm,

2 This invention relates 'Wpc in which one of the pedestals is, provided`with a compartment for housing a typewriter and having means forsupporting the typewriter Patented July 24, `1951 UNITED STATES PATENT[OFFICE METAL FIXTURE FOR TYPEWRITER DESKS Martiens', chicago, inassignor te The sang Company, Chicago, Ill.

y Application April Z7, 1950, Serial No. 158,575

3Claims, (C1. 312--27) to pedestal desks or the in such manner that itmay be. moved from retracted position. inthe compartment to extendedwritingfposition, and more particularly it relates toi an improvedswinging mechanismforthe typewriter platform and a new .arrangement ofcounter-balancing springs. Y The primaryobject of the invention is topro- 1 vide a simple, rugged and dependable mechanism for extending andretracting the typewriter platform of the desk, the mechanism being soarranged that the platform swings in a smooth oontinuous arc fromretracted position to writing position, and makes its final motion intowriting position in an upward and. rearward direction.

Another object of the invention is to provide a mechanism in which thereis` sufficient forward component to theinitial movement of the platformfrom writing position that the platform may be latched in writingposition by engagement of `a` spring latch bar with an upwardly openLlshaped notch.

- .Still another object is to provide a mechanism :in which thecounter-balancing spring is stretched --and in a dead center positionwhen the platform is retracted so that after a slight forward 11u11 onthe platform the spring assists the forward swing thereof substantiallyall the way to writing position.

, The invention is illustrated in a preferred embodiment in theaccompanyingl drawings, in which: Fig. lis a side elevation koi atypewriter desk with the typewriter platform in writing position';` Fig.2 is a plan view thereof with the desk ytop removed, the platform beingin retracted position, and being shown in interrupted lines in writingposition; Fig. 3 is a fragmentary plan view similar to Fig. 2, but on anenlarged scale; Fig. 4 is a section taken as indicated on the line 4 4of Fig. 2; Fig. 5 is a fragmentary sectional View of the latch andlatch-trip mechanism; Fig. 6 is a, fragmentary broken front elevationalview of the latch and latch-trip mechanism; Fig. 7 is a sectional viewsimilar to Fig. 4, but showing the mechanism with the typewriterplatform in a position between retracted and writing positions; Fig. 8is a sectional view similar to Fig. '7 with the platform in writingposition; and Fig. 9 is an enlarged fragmentary sectional view taken asindividing legs, which are joined by panel members II surmounted by atop I2. A typewriter oompartment I3 has a bottom wall I4 and a doormember indicated'at I5.

` .A pair of tracks I5 have mounting brackets I1 at their forward endswhich are screwed to two of the front upright frame members I0 of thedesk, and the rear ends of the tracks are fastened to two rear uprightframe members with screws IB;

`A carriage I9 is provided with a front pair of anti-friction rollers20, and a rear pair of rollers 2l, engaged on opposite sides of thetracks I6. Front bell cranks 22 are pivoted to the carriage at 23, andrear bell cranks 24 are pivoted to th carriage at 25.

. A pair of brackets 26, to which is bolted a typewriter piatform 2, arepivotally connected to the ends of the bell cranks 22 and 24 at 8V forparallel movement; and a pair of parallel side links 23 are pivctallyconnected to the other ends of the bell cranks at 3l).

A pair of guide links 3| are pivotally connected to the side links 29 at32, and are also pivotally comiected` at 33 to a pair oi' upstandinglugs 34 at the front end of the tracks I6. In assembling the mechanismwithin the typewriter compart- .ment of a desk, it is necessary that theguide links y corrugated, annular spring grippers 32uv whichfrictionally grip the Shanks of the studs.

Anl arched cross bar 35 spans the carriage I3 above the rear bell cranks24, and is fastenedA to the carriage at 33. A transverse .bar 31 extendsbetween the rear bell cranks 24 below the pivots v2-3 and in a positionsuch that tension counterbalancing springs 38 which are fastened to thearched cross bar 35 and to the cross bar 31 are in a dead centerposition lwhen the carriage is in its most retracted position-that is,the line of the springs 38 passes substantially .directly through theline of the pivots 25 in said position. Due to this dead centerarrangement of the counter-balancing springs 38, the springs are intheir most elongated condition when the mechanism is fully retracted,and only a slight forward movement of the platform is required to putthe counter-balancing springs 38 into operation to assist in the forwardand upward movement of the typewriter platform` 21.

As best seen in Fig, 5 a pair of latch assembly plates 39 are fastenedinside the upper front about the pivots of the bell cranks.

corners of the typewriter compartment by means of screws 40. A pair ofswinging latch arms 4I are pivoted on the latch plates 39 at 42 and aredrawn downwardly against stop pins 43 by tension springs 44 which arefastened to the swinging arms 4I and to spring lugs 44a. A latch bar 45extends transversely between the swinging arms 4|. When the typewriterplatform 21 is elevated ltoward the writing position shown in Fig. 8,thelatch bar 45 strikes cam surfaces 52 at the rear of the platformbrackets 26, pivoting the latch arms 4l against the tension of spring44, and in writing position the latch bar engages a pair of upwardlyopen notches 46 adjacent the cam surfaces 52 to retain the platform inwritingI position. Mounted at the rear of the typewriter platform 21 isa bifurcated bracket 41 in which a latch-trip 46 is pivoted on a rivet49. The forward portion of thelatch-trip 48 is a finger piece 50, andthe rear portion 5l thereof projects wbeneath the latch bar 45 when theplatform is in writing position. Thus, in order to disengage the latchbar l5 from the upwardly open notches 46 of the platform brackets it'ismerely necessary to depress the finger piece 53 of the latch-trip 48 soas to elevate the swinging latch arms 4I against the tension of thespring 43.

y The operation of the device will be readily understood. When it isdesired to withdraw the `typewriter from the compartment I3, the door'Al5 is opened, the forward end of the typewriter platform 21 is graspedand the platform is pulled forward. The motion of the platform 21 andcarriage I9 causes the guide link 3l to rotate about its pivot 33, thuspivoting the bell cranks 22 and` 24 about their pivots 23 and 25, andbeginning the elevation of the platform 21 in a smooth arc As soon asthe counter-balancing springs. 38 are off their dead center position,the rotation of the bell* cranks and elevation of the platform 21 isassisted by the tension of the counter-balancing g'springs, whichcontinue to exert a lifting force throughout substantially the entiretravel of the platform 21-enough so that the momentum of the platform isalmost sufficient to complete the travel to writing position showninnig; 8 without further effort on the part of the operator. As theplatform reaches writing position, the latch `bar 45 comes into actionas previously described to latch the platform 21 in writing position.The

initial travel of the platform from writing position has suiiicientforward component that the frictional engagement between the latch barand the rear upright surface of thenotch 46 is adequate to maintain theplatform in writing position. Y

The operation of the latch-trip has been prein the art.

lviously described. The mechanism is extremely I claim:` y. l Y

l. A metal fixture for a typewriter desk in which a platform carrying atypewriter may be extended from a compartment and swung up towritingposition, said fixture comprising: tracks for attachment to thewalls of the compartment; a carriage antifrictionally journalled on saidtracks and provided at each side with a front bell crank and a rear bellcrank; brackets for a typewriter platform pivotally mounted on one endof each of said bell cranks for parallel movement; side links connectingthe other ends of the bell cranks; a pair of guide links connecting saidside links to positions near the front ends ofsaid tracks; `and a latchmechanism for releasably securing the platform brackets in writingposition.

2. A metal fixture as specified in claim l wherein the platform bracketshave. upwardly open notches, the latch member is a transverse barmounted on a pair of swinging arms and is spring urged downwardly intoengagement with the open notches, and a latch-trip adapted to besupported by the platform brackets in such a position as to have aportion projecting beneath said transverse bar in writing position, saidlatchtrip being pivotable to elevate the transverse bar and free it fromsaid notches.

3. A metal fixture as specified in claim 1 in which the platformbrackets have upwardly open notches and the latch mechanism comprisesfapair of latch plates adapted to bemounted on the walls of the typewritercompartment, a pair of swinging arms on said latch plates, a transversebar mountedl on said arms to engage said upwardly open notches, andspring means urging said bar downwardly into engagement withthe notches.MARTIN FOX.

' file of this patent:

UNITED STATES PATENTS I Name ADate"- Number Fox June 10, 1341

